Composition of an oligomeric fluorosilane and surface treatment of retroreflective sheet

ABSTRACT

The invention relates to a method of treatment of a retroreflective sheet with a treatment composition that comprises a fluorinated compound having one or more silyl groups and an auxiliary compound selected from the group consisting of (i) one or more non-fluorinated compounds of an element M selected from Si, Ti, Zr, B, Al, Ge, V, Pb and Sn and (ii) an organic compound having a Si—H group. The invention also relates to compositions comprising (i) a fluorinated compound comprising one or more silyl groups and (ii) an auxiliary compound selected from the group consisting of organic compounds having a Si—H group.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. Ser. No. 10/744,684, filed Dec.23, 2003, now allowed, the disclosure of which is incorporated byreference in its entirety herein.

FIELD

The invention relates to fluorinated compositions.

BACKGROUND

Retroreflective articles have the ability to return a substantialportion of incident light in the direction from which the lightoriginated. This unique ability has lead to the widespread use ofretroreflective articles on clothing worn by highway construction andmaintenance workers and fire-fighters. The retroreflective articlesdisplayed on their clothing typically are in the form of retroreflectivestripes. The retroreflective stripes typically comprise a layer ofmicrospheres such as glass beads. The retroreflective articles improvethe wearers' safety by highlighting their presence.

Several basic types of microsphere-containing retroreflective materialsare known. On the one hand, so-called embedded or encapsulated lens typesheetings are known in which the microspheres are covered by atransparent resin layer, i.e., they are fully buried and not exposed toair. The second type of reflective sheeting having microspheres is theso-called open-bead or open-lens material in which the microspheres arepartially exposed to air, i.e., they are not completely buried in abinder layer. A third type of microsphere sheeting is similar to thesecond type, with the exception that a polymeric cover film isheat-sealed intermittently over the microsphere-bearing surface of thereflective sheet. The microspheres in the enclosed lens sheeting areexposed to air (beneath the polymeric cover film), but are not exposedto the elements such as rainfall and are not considered to be open-beadsheeting.

A particular disadvantage of the open-bead reflective sheeting is itsreduced reflectivity under rainfall conditions. Moreover, thereflectivity of the sheeting often diminishes after several launderings.

JP 08-309929 discloses treating the exposed glass bead of an open-beadtype reflective sheet with a combination of a fluorochemical compoundand a silane coupling agent. As the fluorochemical compound, there istaught a perfluoroalkyl acrylic acid ester. Also, it is recommended toadditionally use a melamine resin or an isocyanate crosslinking agent soas to further improve the durability of the treatment.

EP 1,262,802 provides a reflective sheet that comprises a reflectiveelement and that comprises microspheres partially exposed at a majorsurface of the reflective sheet. The reflective sheet has further beentreated with a fluorinated silane compound that has a fluorinated groupand a silane group having one or more hydrolyzable groups.

While some of the known surface treatments may be capable of providingacceptable levels of initial repellent properties, a loss of repellencyis often encountered due to repeated launderings. Further, it would bedesirable to improve the reflective properties of the open-beadreflective sheet material under rainfall conditions.

Accordingly, it is desirable to provide a coating composition capable ofproviding a high durable water repellent coating on a retroreflectivesheet. In particular, it is desirable to provide a durable coatingwherein the initial reflective and repellent properties aresubstantially maintained, even under repeated launderings. It willtypically also be desired that the treatment composition has goodstorage stability, minimal environmental disadvantages and can beconveniently manufactured at minimal costs.

SUMMARY

The invention, in a first aspect, provides a method of treatmentcomprising contacting a retroreflective sheet comprising (i) a binderlayer having at one of its major surfaces a layer of microspheres havinga portion partially embedded in said major surface of said binder layerand having a portion partially protruding therefrom and (ii) areflective layer disposed on the embedded portion of the microspheres,with a treatment composition comprising:

(i) a fluorinated compound having one or more fluorinated groups and oneor more silyl groups that have one or more hydrolysable groups; and

(ii) an auxiliary compound selected from the group consisting of (1) oneor more non-fluorinated compounds of an element M selected from thegroup consisting of Si, Ti, Zr, B, Al, Ge, V, Pb and Sn having at leastone hydrolysable group per molecule, (2) an organic compound having aSi—H group and mixtures thereof.

In a further aspect, the invention provides a composition comprising (i)a fluorinated compound having one or more fluorinated groups and one ormore silyl groups that have one or more hydrolysable groups, and (ii) anauxiliary compound selected from the group consisting of organiccompounds having a Si—H group and mixtures thereof.

In still a further aspect, the invention relates to a composition asdescribed above, further comprising one or more non-fluorinatedcompounds of an element M selected from the group consisting of Si, Ti,Zr, B, Al, Ge, V, Pb and Sn having at least one hydrolysable group permolecule.

It was found that the retroreflective sheets treated by the treatmentmethod of the present invention have improved reflective and repellentproperties. In particular, it was found that the reflectivity and thewater repellency of the treated retroreflective sheets is highlydurable, even after repeated launderings. Furthermore, the reflectivityof the retroreflective sheets under wet conditions, in particularrainfall conditions, is typically improved as a result of the treatment.

DETAILED DESCRIPTION

Fluorinated Compound

Fluorinated compounds suitable for use in the treatment of theretroreflective sheets of the present invention comprise one or morefluorinated groups and one or more silyl groups having one or morehydrolyzable groups. By the term “hydrolyzable group” is meant that thegroups are capable of hydrolyzing under the conditions used to preparethe fluorinated treatment composition and/or the conditions to apply thefluorinated composition to the retroreflective sheet. Such conditionsmay involve the use of a catalyst such as an acid or base. Examples ofsuitable hydrolyzable groups include alkoxy groups, aryloxy groups,halogens such as chlorine, acetoxy groups and acyl groups. Generallypreferred are lower alkoxy groups having 1 to 4 carbon atoms.

The fluorinated compound may contain one or more, for example two orthree, silane groups linked directly to a fluorinated group or they maybe linked to a fluorinated group through an organic linking group. Suchan organic linking group is generally a non-fluorinated group such as ahydrocarbon group and may contain one or more heteroatoms.

The fluorinated compound may comprise any fluorinated group includingfluoroaliphatic groups and fluorinated polyether groups. The fluorinatedgroup of the fluorinated compound may be partially or fully fluorinatedand may be monovalent or multivalent, e.g., divalent. The fluorinatedgroup may further comprise a fluorinated oligomer, derived from thepolymerisation of at least one fluorinated monomer in the presence of achain transfer agent and optionally one or more non-fluorinatedmonomers.

In a particular embodiment the fluorinated compound for use in theinvention is a fluorinated silane corresponding to the formula:R_(f) ¹-[Q-SiY_(3-x)R¹⁰ _(x)]_(y)   (I)wherein

-   R_(f) ¹ represents a monovalent or divalent fluorinated group,-   Q represents an organic divalent linking group,-   R¹⁰ represents a C₁-C₄ alkyl group,-   Y represents a hydrolyzable group;-   x is 0, 1 or 2 and-   y is 1 or 2.

According to a particular embodiment, R_(f) ¹ represents afluoroaliphatic group, which is stable, inert and preferably saturatedand non-polar. The fluoroaliphatic group may be straight chain, branchedchain, or cyclic or combinations thereof and may contain one or moreheteroatoms such as oxygen, divalent or hexavalent sulfur, or nitrogen.The fluoroaliphatic group is preferably fully-fluorinated, but hydrogenor chlorine atoms can be present as substituents if not more than oneatom of either is present for every two carbon atoms. Suitablefluoroaliphatic groups generally have at least 3 and up to 18 carbonatoms, preferably 3 to 14, especially 4 to 10 carbon atoms, andpreferably contain about 40% to about 80% fluorine by weight, morepreferably about 50% to about 79% fluorine by weight. The terminalportion of the fluoroaliphatic group is typically a perfluorinatedmoiety, which will preferably contain at least 7 fluorine atoms, e.g.,CF₃CF₂CF₂—, (CF₃)₂CF—, F₅SCF₂—. The preferred fluoroaliphatic groups arefully or substantially fluorinated and include those perfluorinatedaliphatic radicals of the formula C_(n)F_(2n+1)— where n is 3 to 18,particularly 4 to 10.

According to one embodiment, R¹ _(f) represents a monovalent or divalentpolyfluoropolyether group. The polyfluoropolyether group can includelinear, branched, and/or cyclic structures, and may be saturated orunsaturated. It is preferably a perfluorinated group (i.e., all C—Hbonds are replaced by C—F bonds). More preferably, it includesperfluorinated repeating units selected from the group of—(C_(n)F_(2n))—, —(C_(n)F_(2n)O)—, —(CF(Z))-, —(CF(Z)O)—,—(CF(Z)C_(n)F_(2n)O)—, —(C_(n)F_(2n)CF(Z)O)—, —(CF₂CF(Z)O)—, andcombinations thereof. In these repeating units Z is a perfluoroalkylgroup, an oxygen-substituted perfluoroalkyl group, a perfluoroalkoxygroup, or an oxygen-substituted perfluoroalkoxy group, all of which canbe linear, branched, or cyclic, and preferably have about 1 to about 9carbon atoms and 0 to about 4 oxygen atoms. Examples ofpolyfluoropolyethers containing polymeric moieties made of theserepeating units are disclosed in U.S. Pat. No. 5,306,758 (Pellerite).For the monovalent polyfluoropolyether group (wherein y is 1 in formula(I) above), the terminal groups can be (C_(n)F_(2n+1))—,(C_(n)F_(2n+1)O)— or (X′C_(n)F_(2n)O)—, wherein X′ is H, Cl, or Br, forexample. Preferably, these terminal groups are perfluorinated. In theserepeating units or terminal groups, n is 1 or more, and preferably 1 to4.

Preferred approximate average structures for a divalent fluorinatedpolyether group include —CF₂O(CF₂O)_(m)(C₂F₄O)_(p)CF₂—, wherein anaverage value for m and p is 0 to 50, with the proviso that m and p arenot simultaneously 0, —CF(CF₃)O(CF(CF₃)CF₂O)_(p)CF(CF₃)—,—CF₂O(C₂F₄O)_(p)CF₂—, and —(CF₂)₃O(C₄F₈O)_(p)(CF₂)₃—, wherein an averagevalue for p is 3 to 50. Of these, particularly preferred approximateaverage structures are —CF₂O(CF₂O)_(m)(C₂F₄O)_(p)CF₂—,—CF₂O(C₂F₄O)_(p)CF₂, and —CF(CF₃)O(CF(CF₃)CF₂O)_(p)CF(CF₃)—.Particularly preferred approximate average structures for a monovalentperfluoropolyether group include C₃F₇O(CF(CF₃)CF₂O)_(p)CF(CF₃)— andCF₃O(C₂F₄O)_(p)CF₂— wherein an average value for p is 3 to 50. Assynthesized, these compounds typically include a mixture of polymers.The approximate average structure is the approximate average of themixture of polymers.

The divalent linking group Q can include linear, branched, and/or cyclicstructures, that may be saturated or unsaturated. The group Q cancontain one or more heteroatoms (e.g., oxygen, nitrogen, or sulfur) orfunctional groups (e.g., carbonyl, amido, urethanylene or sulfonamido).Preferably, the divalent linking group Q is a non-fluorinated organicgroup such as a hydrocarbon group, preferably, a linear hydrocarbongroup, optionally containing heteroatoms or functional groups, and morepreferably, containing at least one functional group. Examples of Qgroups include —C(O)NH(CH₂)₃—, —CH₂O(CH₂)₃—, —CH₂OC(O)N(R)(CH₂)₃—,wherein R is H or lower alkyl group, and —(C_(n)H_(2n))—, wherein n isabout 2 to about 6. A typical linking group Q is —C(O)NH(CH₂)₃—.

Y represents a hydrolyzable group in formula (I) such as for example ahalogen, a C₁ -C₄ alkoxy group, an acyloxy group, an acyl group or apolyoxyalkylene group, such as polyoxyethylene groups as disclosed inU.S. Pat. No. 5,274,159. Specific examples of hydrolyzable groupsinclude methoxy, ethoxy and propoxy groups, chlorine and an acetoxygroup.

Compounds of formula (I) suitable for use in the present inventiontypically have a molecular weight (number average) of at least about200, and preferably, at least about 1000. Preferably, they are nogreater than about 10000.

Examples of preferred fluorinated silane compounds according to formula(I) include, but are not limited to, the following approximate averagestructures: XCF₂O(CF₂O)_(m)(C₂F₄O)_(p)CF₂X,C₃F₇O(CF(CF₃)CF₂O)_(p)CF(CF₃)X, XCF(CF₃)O(CF(CF₃)CF₂O)_(p)CF(CF₃)X,XCF₂O(C₂F₄O)_(p)CF₂X, and CF₃O(C₂F₄O)_(p)CF₂X,X(CF₂)₃O(C₄F₈O)_(p)(CF₂)₃X, wherein —X is -Q-SiY_(3-x)R¹⁰ _(x) asdefined above in formula (I) or a nonsilane-containing terminal group asdefined above ((C_(n)F_(2n+1))—, (CnF_(2n+1)O)— or (X′C_(n)F_(2n)O)—wherein X′ is H, Cl, or Br), with the proviso that at least one X groupper molecule is a silane). Preferably, in each fluorinated polyethersilane, Q contains a nitrogen atom. More preferably, at least one Xgroup per molecule is C(O)NH(CH₂)₃Si(OR)₃ (wherein R is methyl, ethyl,polyethyleneoxy or mixtures thereof), and the other X group, if not asilane, is OCF₃, or OC₃F₇. The values of m and p in these approximateaverage structures can vary. Preferably, an average value of m is withina range of about 1 to about 50, and an average value of p is within arange of about 4 to about 40. As these are polymeric materials, suchcompounds exist as mixtures upon synthesis, which are suitable for use.These mixtures may also contain perfluoropolyether chains bearing nofunctional groups (inert fluids) or more than two terminal groups(branched structures) as a consequence of the methods used in theirsynthesis. Typically, mixtures of polymeric materials containing lessthan about 10% by weight of non-functionalized polymers (e.g., thosewithout silane groups) can be used. Furthermore, mixtures of any of theindividually listed compounds of formula (I) can be used.

Compounds of formula (I) can be synthesized using standard techniquesand are commercially available. For example, commercially available orreadily synthesized fluorinated polyether esters can be combined with afunctionalized alkoxysilane, such as a 3-aminopropylalkoxysilane,according to U.S. Pat. No. 3,810,874 (Mitsch et al.). Such materials mayor may not need to be purified before use in a method of treatment or acomposition according to the invention.

According to a further embodiment the fluorinated compounds for use inthe invention can be derived from fluorinated oligomers having one ormore silyl groups that have one or more hydrolysable groups as definedabove. The fluorinated oligomers can be prepared by free-radicaloligomerization of at least one fluorinated monomer in the presence of achain transfer agent and optionally one or more non-fluorinated monomersand wherein at least one of said non-fluorinated monomers and/or chaintransfer agent comprises a silyl group that has one or more hydrolysablegroups.

Fluorochemical oligomers for use in this invention include those thatmay be represented by the general formula (II):A-M^(f) _(q)M^(h) _(r)M^(a) _(s)-G   (II)wherein A represents the residue of an initiator or hydrogen;

-   M^(f) represents units derived from fluorinated monomers;-   M^(h) represents units derived from non-fluorinated monomers;-   M^(a) represents units having a silyl group represented by the    formula:    wherein each of Y⁴,Y⁵ and y⁶ independently represents an alkyl    group, an aryl group or a hydrolyzable group;-   G is a monovalent organic group comprising the residue of a chain    transfer agent;-   q represents a value of 1 to 100;-   r represents a value of 0 to 100;-   s represents a value of 0 to 100;-   and q+r+s is at least 2;-   with the proviso that at least one of the following conditions is    fulfilled: (a) G is a monovalent organic group that contains a silyl    group of the formula:    wherein Y¹, Y² and Y³ each independently represents an alkyl group,    an aryl group or a hydrolyzable group with at least one of Y¹, Y²    and Y³ representing a hydrolyzable group or (b) s is at least 1 and    at least one of Y⁴, Y⁵ and Y⁶ represents a hydrolyzable group.

The silyl groups having one or more hydrolysable groups can be includedin the fluorochemical oligomer by copolymerising the fluorochemicalmonomer with a monomer having a silyl group that has one or morehydrolyzable groups or through the use of a chain transfer agent thatincludes such a silyl group. Alternatively, a functionalised chaintransfer agent or functionalised comonomer can be used which can bereacted with a reagent having a silyl group having one or morehydrolyzable groups subsequent to the oligomerization.

The total number of units represented by the sum of q, r and s isgenerally at least 2 and preferably at least 3 so as to render thecompound oligomeric. The value of q in the fluorochemical oligomer isbetween 1 and 100 and preferably between 2 and 20. The values of r and sare between 0 and 100 and preferably between 1 and 30. According to apreferred embodiment, the value of r is less than that of q and q+r+s isat least 2.

The fluorinated oligomer silanes according to formula (II) typicallyhave an average molecular weight between 400 and 100000, preferablybetween 600 and 20000. The fluorochemical silane preferably contains atleast 10 mole % (based on total moles of units M^(f), M^(h) and M^(a))of hydrolysable groups.

It will further be appreciated by one skilled in the art that thepreparation of fluorochemical oligomers results in a mixture ofcompounds and accordingly, general formula (II) should be understood asrepresenting a mixture of compounds whereby the indices q, r and s informula (II) represent the molar amount of the corresponding unit insuch mixture. Accordingly, it will be clear that q, r and s can befractional values.

The units M^(f) of the fluorochemical oligomer are generally derivedfrom fluorochemical monomers corresponding to the formula:R² _(f)-Q¹-E¹   (III)wherein R² _(f) represents a fluoroaliphatic group containing at least 3carbon atoms or a fluorinated polyether group. Q¹ represents an organicdivalent linking group and E¹ represents a free radical polymerizablegroup.

The fluoroaliphatic group R² _(f), in the fluorochemical monomer, is afluorinated, stable, inert, preferably saturated, non-polar, monovalentaliphatic radical. It can be straight chain, branched chain, or cyclicor combinations thereof. It can contain heteroatoms such as oxygen,divalent or hexavalent sulfur, or nitrogen. R² _(f) is preferably afully-fluorinated radical, but hydrogen or chlorine atoms can be presentas substituents if not more than one atom of either is present for everytwo carbon atoms. The R² _(f) radical has at least 3 and up to 18 carbonatoms, preferably 3 to 14, especially 4 to 10 carbon atoms, andpreferably contains about 40% to about 80% fluorine by weight, morepreferably about 50% to about 79% fluorine by weight. The terminalportion of the R² _(f) radical is a perfluorinated moiety, which willpreferably contain at least 7 fluorine atoms, e.g., CF₃CF₂CF₂—,(CF₃)₂CF—, F₅SCF₂—. The preferred R² _(f) radicals are fully orsubstantially fluorinated and are preferably those perfluorinatedaliphatic radicals of the formula C_(n)F_(2n+1)— where n is 3 to 18,particularly 4 to 10.

The R² _(f) group can further represent a monovalent polyfluoropolyethergroup, as for example defined above with respect to R¹ _(f).

M^(f) in formula (II) can also be derived from a difunctionalfluorochemical monomer corresponding to the formula:E^(a)-Q^(a)-R³ _(f)-Q^(b)-E^(b)   (IV)wherein Q^(a) and Q^(b) each independently represents an organicdivalent linking group and E^(a) and E^(b) each independently representa free radical polymerizable group. R³ _(f) represents a divalentperfluoropolyether group such as —(CF(CF₃)CF₂O)_(p)—,—(CF₂O)_(p)(CF₂CF₂O)_(q)—, —CF(CF₃)(CF₂CF(CF₃)O)_(p)CF(CF₃)O—,—(CF₂O)_(p)(CF₂CF₂O)_(q)CF₂—, —(CF₂CF₂O)_(p)—, —(CF₂CF₂CF₂O)_(p)—,wherein an average value for p and q is 1 to about 50. The molecularweight of the difunctional fluorochemical monomer should generally bebetween about 200 and 3000, more preferably between 300 and 2500. Theamount of difunctional fluorochemical monomer used should be chosen soas to obtain a composition which is soluble or dispersible in an organicsolvent or in water.

The linking groups Q¹, Q^(a) and Q^(b) in the above formulae (III) and(IV) link the fluoroaliphatic or the fluorinated polyether group R² _(f)or R³ _(f) to the free radical polymerizable group E¹, E^(a) or E^(b)and are generally non-fluorinated organic linking groups. The linkinggroups preferably contain from 1 to about 20 carbon atoms and mayoptionally contain oxygen, nitrogen, or sulfur-containing groups or acombination thereof. The linking groups are preferably free offunctional groups that substantially interfere with free-radicaloligomerization (e.g., polymerizable olefinic double bonds, thiols, andother such functionality known to those skilled in the art). Examples ofsuitable linking groups Q^(1,a,b) include straight chain, branched chainor cyclic alkylene, arylene, aralkylene, oxy, oxo, hydroxy, thio,sulfonyl, sulfoxy, amino, imino, sulfonamido, carboxyamido, carbonyloxy,urethanylene, ureylene, and combinations thereof such assulfonamidoalkylene. Preferred linking groups are selected from thegroup consisting of alkylene and an organic divalent linking groupaccording to the following formulae:

wherein R¹¹ represents a hydrogen or a linear or branched alkylenehaving 2 to 4 carbon atoms and R¹² represents a hydrogen or an alkylhaving 1 to 4 carbon atoms.

E¹, E^(a) and E^(b) are free radically polymerizable groups thattypically contain an ethylenically unsaturated group capable ofundergoing a free radical polymerization. Suitable groups include, forexample, moieties derived from vinyl ethers, vinyl esters, allyl esters,vinyl ketones, styrene, vinyl amide, acrylamides, maleates, fumarates,acrylates and methacrylates. Of these, the esters of alpha, betaunsaturated acids, such as the acrylates and methacrylates arepreferred.

Fluorochemical monomers R² _(f)-Q¹-E¹ as described above and methods forthe preparation thereof are known and disclosed, e.g., in U.S. Pat.No.2,803,615. Examples of such compounds include general classes offluorochemical acrylates, methacrylates, vinyl ethers, and allylcompounds containing fluorinated sulfonamido groups, acrylates ormethacrylates derived from fluorochemical telomer alcohols, acrylates ormethacrylates derived from fluorochemical carboxylic acids, andperfluoroalkyl acrylates or methacrylates as disclosed in EP 526 976.

Fluorinated polyetheracrylates or methacrylates are described in U.S.Pat. No. 4,085,137.

Typical examples of fluorochemical monomers include:

wherein R represents methyl, ethyl or n-butyl and u and v are about 1 to50.

The units M^(h) of the fluorinated oligomer silane (when present) aregenerally derived from a non-fluorinated monomer, preferably a monomerconsisting of a polymerizable group and a hydrocarbon moiety.

Examples of non-fluorinated monomers from which the units M^(h) can bederived include general classes of ethylenic compounds capable offree-radical polymerization, such as, for example, allyl esters such asallyl acetate and allyl heptanoate; alkyl vinyl ethers or alkyl allylethers such as cetyl vinyl ether, dodecylvinyl ether, 2-chloroethylvinylether, ethylvinyl ether; unsaturated acids such as acrylic acid,methacrylic acid, alpha-chloro acrylic acid, crotonic acid, maleic acid,fumaric acid, itaconic acid and their anhydrides and their esters suchas vinyl, allyl, methyl, butyl, isobutyl, hexyl, heptyl, 2-ethylhexyl,cyclohexyl, lauryl, stearyl, isobornyl or alkoxy ethyl acrylates andmethacrylates; alpha-beta unsaturated nitriles such as acrylonitrile,methacrylonitrile, 2-chloroacrylonitrile, 2-cyanoethyl acrylate, alkylcyanoacrylates; alpha,beta-unsaturated carboxylic acid derivatives suchas allyl alcohol, allyl glycolate, acrylamide, methacrylamide,n-diisopropyl acrylamide, diacetoneacrylamide,N,N-diethylaminoethylmethacrylate, N-t-butylamino ethyl methacrylate;styrene and its derivatives such as vinyltoluene, alpha-methylstyrene,alpha-cyanomethyl styrene; lower olefinic hydrocarbons which can containhalogen such as ethylene, propylene, isobutene, 3-chloro-1-isobutene,butadiene, isoprene, chloro and dichlorobutadiene and2,5-dimethyl-1,5-hexadiene, and allyl or vinyl halides such as vinyl andvinylidene chloride. Preferred non-fluorinated monomers includehydrocarbon group containing monomers such as those selected fromoctadecylmethacrylate, laurylmethacrylate, butylacrylate, N-methylolacrylamide, isobutylmethacrylate, ethylhexyl acrylate and ethylhexylmethacrylate; and vinylchloride and vinylidene chloride.

The fluorinated oligomer having one or more silyl groups, useful in theinvention generally further includes units M^(a) that have a silyl groupthat has one or more hydrolysable groups. Examples of units M^(a)include those that correspond to the general formula:

wherein R¹³, R¹⁴ and R¹⁵ each independently represents hydrogen, analkyl group such as for example methyl or ethyl, halogen or an arylgroup, L represents an organic divalent linking group and Y⁷, Y⁸ and Y⁹independently represents an alkyl group, an aryl group, or ahydrolysable group.

Such units M^(a) may be derived from a monomer represented by theformula:

wherein each of Y⁷, Y⁸ and Y⁹ independently represents an alkyl group,an aryl group, or a hydrolysable group; L represents a chemical bond oran organic divalent linking group and E² represents a free radicalpolymerizable group such as for example listed above with respect to E¹.Alternatively such units M^(a) according to formula (V) can be obtainedby reacting a functionalized monomer with a silyl group containingreagent. By the term “functionalised monomer” is meant a monomer thathas one or more groups available for subsequent reaction, for example agroup capable of undergoing a condensation reaction. Typically, thefunctionalised monomer is a monomer that has one or more groups capableof reacting with isocyanate or epoxy groups. Specific examples of suchgroups include hydroxy and amino groups. Examples of silyl groupcontaining reagents include e.g., 3-isocyanatopropyltrimethoxysilane or3-epoxypropyltrimethoxysilane.

When L represents an organic divalent linking group, it preferablycontains from 1 to about 20 carbon atoms. L can optionally containoxygen, nitrogen, or sulfur-containing groups or a combination thereof,and L is preferably free of functional groups that substantiallyinterfere with free-radical oligomerization (e.g., polymerizableolefinic double bonds, thiols, and other such functionality known tothose skilled in the art). Examples of suitable linking groups L includestraight chain, branched chain or cyclic alkylene, arylene, aralkylene,oxyalkylene, carbonyloxyalkylene, oxycarboxyalkylene,carboxyamidoalkylene, urethanylenealkylene, ureylenealkylene andcombinations thereof. Preferred linking groups are selected from thegroup consisting of alkylene, oxyalkylene and carbonyloxyalkylene.According to a particularly preferred embodiment, the linking group Lcorresponds to the formula:

wherein Q³ and Q⁴ independently represents an organic divalent linkinggroup. Examples of organic divalent linking groups Q³ include forexample an alkylene, an arylene, oxyalkylene, carbonyloxyalkylene,oxycarboxyalkylene, carboxyamidoalkylene, urethanylenealkylene andureylenealkylene. Examples of organic divalent linking groups Q⁴ includefor example alkylene and arylene. T represents O or NR wherein Rrepresents hydrogen, a C₁-C₄ alkyl group or an aryl group.

Y⁷, Y⁸ and Y⁹ independently represents an alkyl group, an aryl group ora hydrolysable group.

Examples of monomers according to formula (VI) includevinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane andalkoxysilane functionalised acrylates or methacrylates, such asmethacryloyloxypropyl trimethoxysilane.

The fluorinated oligomer having one or more silyl groups is convenientlyprepared in the presence of a chain transfer agent. Suitable chaintransfer agents typically include a hydroxy-, amino-, mercapto orhalogen group. The chain transfer agent may include two or more of suchhydroxy, amino-, mercapto or halogen groups. Typical chain transferagents useful in the preparation of the fluorinated oligomer includethose selected from 2-mercaptoethanol, 3-mercapto-2-butanol,3-mercapto-2-propanol, 3-mercapto-1-propanol,3-mercapto-1,2-propanediol, 2-mercapto-ethylamine,di(2-mercaptoethyl)sulfide, octylmercaptane and dodecylmercaptane.Further, the chain transfer agent may be a polysiloxane having one ormore mercapto groups.

In a preferred embodiment a chain transfer agent containing a silylgroup having one or more hydrolyzable groups is used in theoligomerization to produce the fluorinated oligomer. Chain transferagents including such a silyl group include those according to formula(VII).

wherein Y¹⁰, Y¹¹ and Y¹² each independently represents an alkyl group,preferably a C₁-C₈ alkyl group such as methyl, ethyl or propyl or analkyl group containing a cycloalkyl such as cyclohexyl or cylcopentyl,an aryl group such as phenyl, an alkylaryl group or an aralkyl group, ahydrolysable group such as for example halogen or alkoxy group such asmethoxy, ethoxy or aryloxy group, with at least one of Y¹⁰, Y¹¹ and Y¹²representing a hydrolysable group. L¹ represents a divalent linkinggroup.

Preferred chain transfer agents are those in which L¹ represents —S-Q⁵-with Q⁵ being linked to the silicone atom in formula (VII) and whereinQ⁵ represents an organic divalent linking group such as for example astraight chain, branched chain or cyclic alkylene, arylene oraralkylene. The use of such chain transfer agent will generally resultin fluorinated oligomers in which the monovalent organic group Gcorresponds to the following formula:

wherein Y¹⁰, Y¹¹, Y¹² and Q⁵ have the meaning as defined above.

A single chain transfer agent or a mixture of different chain transferagents may be used. The preferred chain transfer agents are2-mercaptoethanol, octylmercaptane and 3-mercaptopropyltrimethoxysilane.A chain transfer agent is typically present in an amount sufficient tocontrol the number of polymerized monomer units in the oligomer and toobtain the desired molecular weight of the oligomeric fluorinatedsilane. The chain transfer agent is generally used in an amount of about0.05 to about 0.5 equivalents, preferably about 0.25 equivalents, perequivalent of monomer including fluorinated and non-fluorinatedmonomers.

The fluorinated oligomer silane for use in the present inventioncontains one or more hydrolyzable groups. These hydrolysable groups maybe introduced in the fluorinated silane by oligomerising in the presenceof a chain transfer agent having a silyl group containing one or morehydrolysable groups, for example a chain transfer agent according toformula (VII) above wherein at least one of Y¹⁰, Y¹¹ and Y¹² representsa hydrolysable group and/or by co-oligomerising with a monomercontaining a silyl group having one or more hydrolysable groups such asa monomer according to formula (VI) above wherein at least one of Y⁷, Y⁸and Y⁹ represents a hydrolysable group. Alternatively, a functionalisedchain transfer agent or functionalised comonomer can be used which canbe reacted with a silyl group containing reagent subsequent to theoligomerization.

The fluorinated oligomer having one or more silyl groups, for use in thepresent invention, can be prepared through a free radical polymerisationas described in EP 1 225 187.

The amount of fluorinated compound having one or more fluorinated groupsand one or more silyl groups for use in the present invention may varywidely and the optimal amount can be determined by one skilled in theart through experimentation. Typically, an amount of 1% by weight to 90%by weight, preferably between 10% by weight and 85% by weight, morepreferably between 20% by weight to 80% by weight on the total weight offluorinated compound and auxiliary compounds is included in thetreatment composition.

Auxiliary Compound

Non-Fluorinated Compound of Element M

The composition useful in the present invention comprises one or morenon-fluorinated compounds of an element M selected from the groupconsisting of Si, Ti, Zr, B, Al, Ge, V, Pb and Sn having at least onehydrolysable group per molecule. Preferably, the hydrolysable groups aredirectly bonded to the element M.

In one embodiment of the present invention, the non-fluorinated compoundof element M comprises a compound according to the formula (VIII):(R)_(i)M(Y)_(j-i)   (VIII)wherein R represents a non-hydrolysable group, M represents an elementselected from the group consisting of Si, Ti, Zr, B, Al, Ge, V, Pb andSn, j is 3 or 4 depending on the valence of M, i is 0,1 or 2, and Yrepresents a hydrolysable group.

The hydrolysable groups present in the non-fluorinated compound ofelement M may be the same or different and are generally capable ofhydrolyzing under appropriate conditions, for example under acidic orbasic aqueous conditions, such that the non-fluorinated compound ofelement M can undergo condensation reactions. Preferably, thehydrolysable groups upon hydrolysis yield groups capable of undergoingcondensation reactions, such as hydroxyl groups.

Typical and preferred examples of hydrolysable groups include those asdescribed with respect to the fluorinated compound. Preferably, thenon-fluorinated compound of element M includes tetra-, tri- or dialkoxy(preferably containing 1 to 4 carbon atoms) compounds.

The non-hydrolysable groups R may be the same or different and aregenerally not capable of hydrolyzing under the conditions listed above.For example, the non-hydrolysable groups R may be independently selectedfrom a hydrocarbon group, for example a C₁-C₃₀ alkyl group, which may bestraight chained or branched and may include one or more aliphatic,cyclic hydrocarbon structures, a C₆-C₃₀ aryl group (optionallysubstituted by one or more substituents selected from halogens and C₁-C₄alkyl groups), or a C₇-C₃₀ aralkyl group.

In one embodiment the non-hydrolysable groups R are independentlyselected from a hydrocarbon group, for example a C₁-C₃₀ alkyl group anda C₆-C₂₀ aryl group (optionally substituted by one or more substituentsselected from halogens and C₁-C₄ alkyl groups).

Preferred non-fluorinated compound of element M include those in which Mis Ti, Zr, Si or Al.

Representative examples of non-fluorinated compound of element M includetetramethoxy silane, tetraethoxysilane, methyltriethoxysilane, dimethyldiethoxysilane, octadecyl triethoxysilane, methyltrichlorosilane,tetramethyl orthotitanate, tetraethyl orthotitanate, tetra-iso-propylorthotitanate, tetra-n-propyl orthotitanate,tetra(2-ethylhexyl)orthotitanate, tetraethyl zirconate, tetra-iso-propylzirconate, tetra-n-propyl zirconate and the like. More preferredcompounds include C₁-C₄ alkoxy derivatives of Si, Ti and Zr.Particularly preferred non-fluorinated compounds of element M includetetra ethoxysilane. Single compounds or mixtures of non-fluorinatedcompounds of element M may be used. Non-fluorinated compound of elementM can be completely or partially hydrolysed or precondensed beforeaddition to the fluorinated treatment composition.

The amount of non-fluorinated compound of an element M for use in thepresent invention may vary widely and the optimal amount can be readilydetermined by one skilled in the art by routine experimentation.Typically the compound may be included in the composition in an amountup to 99% by weight, preferably between 10 and 80% by weight based onthe total weight of fluorinated compound and auxiliary compounds.

Organic Compound Having Si—H Group

The organic compound having one or more Si—H groups for use with thisinvention may be a non-polymeric organic compound or can be a polymericorganic compound. By “polymeric compound” is meant that the compoundcomprises repeating units that are actually or conceptually derived fromlower molecular weight compounds, i.e., monomers. The polymerizationdegree may vary widely and includes a low polymerization degree such asfor example a polymerization degree of 2 to 50 repeating units as wellas a large polymerization degree of more than 50. Thus, the term“polymeric compound” should be understood to include oligomericcompounds that typically have a low polymerization degree. If theorganic compound is polymeric, the SiH function may be contained in theterminating group of the polymeric chain and/or in a repeating unit ofthe polymeric compound. The organic compound having a Si—H group istypically a non-fluorinated compound.

In accordance with a preferred embodiment in connection with the presentinvention, the organic compound having a Si—H group is a polysiloxane(oligomer or polymer), comprising a polysiloxy backbone. Such polymer oroligomer may be terminated by a group containing one or more Si—Hfunctions and/or may contain Si—H groups distributed along the backbone.The Si—H groups may form part of the backbone or they can be present ina side group attached to the backbone.

For example, the polysiloxanes for use with this invention include thosethat correspond to the formula:

wherein R¹, R², R³, R⁶, R⁷, R⁸ and R⁹ each independently representshydrogen, an alkoxy group, an alkyl optionally substituted such as forexample with an aryl group, an ester, an alkoxy etc., or aryl groupoptionally substituted such as for example with an alkyl group, anester, an alkoxy etc., R⁴ and R⁵ each independently represents an alkoxygroup, an alkyl or aryl group each of which may optionally besubstituted, x represents a value of 0 to 150, y represents a value of 0to 150 and with the proviso that when x=0, at least one of R¹, R², R⁶,R⁷, R⁸ and R⁹ represents a hydrogen atom.

Specific examples of siloxanes include 1,1,3,3 tetraisopropyldisiloxane, diphenyl-1,1,3,3 tetrakis(dimethylsiloxy)disiloxaneavailable from United Chem, silylhydride terminatedpoly(dimethylsiloxane), poly(methyl hydro siloxane) and copolymers ofdimethylsiloxane and methylhydrosiloxane,polyethyl hydrosiloxane, polyphenyl dimethylhydrosiloxy siloxane, copolymers of methylhydrosiloxaneand octyl methyl siloxane and, copolymers of methyl hydrosiloxane andphenyl methyl siloxane.

Further siloxanes that can be used may be cyclic such as thosecorresponding to the formula:

wherein R^(c) represents hydrogen, an alkyl group or an aryl group,R^(d) and R^(e) each independently represents an alkyl or aryl group, kis at least 1 and the sum of k+1 is at least 3. Specific examples ofcyclic siloxanes according to the above formula are 1,3,5-trimethylcyclosiloxane and 1 phenyl-3,3,5,5-tetramethyl cyclosiloxane.

Polysiloxanes and siloxanes having SiH groups are known in the art andcan be produced according to well-known procedures such as disclosed infor example: Encyclopedia of Polymer Science and Engineering, SecondEdition, V15, Silicones, pas. 204-308, John Wiley & Sons, 1989.Siloxanes having SiH groups are also generally commercially available.Preferably, the siloxane or polysiloxane will have a molecular weightbetween 150 g/mol and 70 000 g/mol

The amount of organic compound having a Si—H group for use in thepresent invention may vary widely. Typically, the Si—H containingcompound may be included in the composition in an amount of up to 90% byweight, preferably between 5% by weight and 60% by weight based on thetotal weight of fluorinated compound and auxiliary compounds.

Retroreflective Sheet

The retroreflective sheet for use in the invention comprises (i) abinder layer having at one of its major surfaces a layer of microsphereshaving a portion partially embedded in said major surface of said binderlayer and having a portion partially protruding therefrom and (ii) areflective layer disposed on the embedded portion of the microspheres.

Binder Layer

The binder layer typically comprises a flexible fluid-impermeablepolymeric material that stabilizes the retroreflective sheet andsupports the reflective optical system comprising the reflective layerand the micropheres. The polymeric material of the binder layer mayinclude various elastomers, as well as thermoplastic binders wherein thebinder attains a liquid or softened state via heating until molden.Preferably, the polymeric material includes a crosslinked or virtuallycrosslinked elastomer. A crosslinked elastomer means that the polymericchains of the elastomer are chemically crosslinked to form a threedimensional network which is stabilized against molecular flow. Avirtually crosslinked elastomer means that the polymeric chain mobilityof the elastomer is greatly reduced by chain entanglement and/or byhydrogen bonding, resulting in an increase in the cohesive or internalstrength of the polymer. Examples of such polymer crosslinking includecarbon-carbon bond formation such as: free radical bonding between vinylgroups between chains; agent or group coupling such as by vulcanizationor reaction with a coupling agent such as a diol in the case ofisocyanate or epoxy functionalized polymers; a diisocyanate or anactivated ester in the case of amine and alcohol functionalizedpolymers; and epoxides and diols in the case of carboxylic acid oranhydride functionalized polymers. Examples of such virtual crosslinkinginclude amide hydrogen bonding as is found in polyamides or crystallineand amorphous region interactions as is found in block copolymers ofstyrene and acrylonitrile.

The binder layer also may contain optional additives such as stabilizers(for example, thermal and hydrolytic stabilizers), antioxidants, flameretardants, and flow modifiers (for example, surfactants), viscosityadjusters (for example, organic solvents), rheology modifiers (forexample, thickeners), coalescing agents, plasticizers, tackifiers, andthe like. The binder layer may be transparent, but commonly comprisescolorants, such as for example, pigments, dyes or metal flakes asdescribed in U.S. Pat. No. 5,812,317 (Billingsley) to provide specialcolors and visual effects. Generally, the binder layer contains fromabout 70% by weight up to about 99% by weight of a polymeric materialwith the remainder being optional additives in effective amounts.

Illustrative examples of the polymers that may be employed in the binderlayer include: polyacrylates, polyolefins; polyesters; polyurethanes;polyepoxides; natural and synthetic rubbers; and combinations thereof.Examples of crosslinked polymers include the foregoing examples ofpolymers substituted with crosslinkable groups such as epoxide groups,olefinic groups, isocyanate groups, alcohol groups, amine groups oranhydride groups. Multifunctional monomers and oligomers which reactwith functional groups of the polymers may also be used as crosslinkers.

Specific examples of useful binder layer materials are disclosed in U.S.Pat. Nos. 5,200,262 and 5,283,101. In the '262 patent, the binder layercomprises one or more flexible polymers having active hydrogenfunctionalities such as crosslinked urethane-based polymers (forexample, isocyanate cured polyesters or one of two componentpolyurethanes) and one or more isocyanate-functional silane couplingagents. In the '101 patent, the binder layer comprises an electron-beamcured polymer selected from the group consisting of chlorosulfonatedpolyethylenes, ethylene copolymers comprising at least about 70 weightpercent polyethylene, and poly(ethylene-co-propylene-co diene) polymers.

Examples of commercially available polymers that may be used in thebinder layer of the retroreflective sheet include Vitel™ 3550, Vitel™VPE 5545 and VPE 5833 polyesters available from Shell Oil Company;Rhoplex™ HA-8 and NW-1845 acrylic resins available from Rohm and Haas;Cydrothane™ a polyurethane available from Cytec Industries of AmericanCyanamide; Estane™ 5703 and 5715 available from B.F. Goodrich, Nipol™1000, available from Zeon Chemicals and acrylonitrile butadiene rubbers,available from ABCR.Binder layers comprising compositions that aredurable, resistant to laundering and non-corrosive to the adjacentreflective elements are preferred.

An adhesion promoter may also be present in the binder layer in theamounts of 0.2% to about 1.5% by weight. Adhesion promoters are commonlyaminosilanes such as aminomethyltrimethoxysilane,aminopropyltriethoxysilane, etc.

The binder layer may further be comprised of two or more layers. Forexample the binder layer may be comprised of one or more layerscomprising an adhesion promoter and a layer that does not contain anadhesion promoter.

The binder layer preferably has a thickness of about 50 to 250 μm, morepreferably about 75 to 200 μm. A binder layer having a thickness outsidethese ranges may be used. However, if the binder layer is too thin, itmay not provide sufficient support to the retroreflective element andthe microspheres and the microspheres may become dislodged. If thebinder layer has a thickness of over 200 μm, it may unnecessarilystiffen the article and add to its cost.

The binder layer may also comprise a polymer composition which hasinherent properties of an adhesive as described in U.S. Pat. No.5,674,605 (Marecki), so that the binder layer may be used in certaininstances to bond the reflective sheet to a garment or accessory withoutthe use of additional adhesive.

Microspheres

The retroreflective sheet comprises a monolayer of microspheres having ahemispheric reflective layer disposed thereon. The microspheres arepartially embedded in and partially protruding from the front or thefirst major surface of the binder layer. The microspheres supported bythe binder layer are capable of collimating light so that incident lightis returned in a direction substantially parallel to the direction fromwhich the light came. The microspheres preferably are substantiallyspherical in shape to provide uniform and efficient retroreflection. Themicrospheres also preferably are substantially transparent to minimizelight absorption by the microspheres and thereby optimize the amount oflight that is retroreflected by the article. The term transparent meansthat when viewed under an optical microscope (e.g., at 100×) themicrospheres have the property of transmitting rays of visible light sothat bodies beneath the microspheres, such as bodies of the same natureas the microspheres can be clearly seen through the microspheres, whenboth are immersed in oil of approximately the same refractive index asthe microspheres. The outline, periphery or edges of bodies beneath themicrospheres are clearly discernible. Although the oil should have arefractive index approximating that of the microspheres, it should notbe so close that the microspheres seem to disappear as would be the casefor a perfect match. The microspheres typically are substantiallycolorless but may be colored to produce special effects.

Transparent microspheres may be made from inorganic materials, such asglass or a non-vitreous ceramic composition, or can be made from organicmaterials such as a synthetic resin which possesses the required opticalproperties and physical characteristics needed for retroreflection. Ingeneral, glass and ceramic microspheres are preferred because they canbe harder and more durable than microspheres made from synthetic resins.

Microspheres used in the present invention preferably have an averagediameter of about 30 to 200 micrometers (μm), more preferably 40 to 90μm. Microspheres smaller than 30 μm may tend to provide lower levels ofretroreflection because of diffraction effects; whereas, microsphereslarger than 200 μm may tend to impart undesirably rough texture to thearticle or undesirably reduce the flexibility thereof. Microspheres usedin this invention preferably have a refractive index of about 1.7 toabout 2.0, the range typically considered to be useful inmicrosphere-based retroreflective products where, as here, the frontsurface of the microspheres are exposed or air-incident. Examples ofmicrospheres that may be useful in the present invention are disclosedin the following U.S. Pat. Nos. 1,175,224, 2,461,011, 2,726,161,2,842,446, 2,853,393, 2,870,030, 2,939,797, 2,965,921, 2,992,122,3,468,681, 3,946,130, 4,192,576, 4,367,919, 4,564,556, 4,758,469,4,772,511, and 4,931,414.

The refractive index and the size of the microsphere are selected sothat the microsphere focuses the incident light at a point roughlycoincident with the location of the reflective layer. By appropriateselection of these parameters, the microsphere can easily focus theincident light at a point near the back surface of the microsphere orslightly behind the surface of the microsphere.

Reflective Layer

The retroreflective sheet further comprises a reflective layer in orderto reflect light. The reflective layer is disposed on the embeddedportions of the micropheres to reflect light incident thereupon. Thelanguage “disposed on the embedded portion of the microspheres” meansthat the reflective layer is in direct contact with the microspheres (onthe embedded portion) or is in contact with the microspheres throughanother reflective layer (for example, a dielectric mirror) ornon-reflecting, so called light transmissible intermediate layer, aswill be described furtheron.

The reflective layer may comprise reflective pigments or may be areflective metal layer. The term “reflective metal layer” is used hereinto mean a reflective layer comprising an effective amount of elementalmetal to reflect incident light, preferably specularly reflect incidentlight. A variety of metals may be used to provide a specular reflectivemetal layer. These include aluminum, silver, chromium, nickel,magnesium, gold, and alloys thereof, in elemental form. Aluminum andsilver are the preferred metals for use in the reflective metal layer.The reflective metal layer may be a continuous coating and may beproduced by vacuum deposition, vapor-coating chemical deposition, orelectroless plating techniques. Vacuum diposition and vapour coatingtechniques are preferred. Vapour coating means creating a stream ofmetal molecules or particles in a vacuum by techniques including, butnot limited to evaporating and sputtering. The vapour coating operationmay be achieved by placing a metal in an evaporator which is heated in avacuum to a temperature high enough to vaporize the metal. Usually thevacuum pressure is about 0.133 to 1.33 pascals. Sputtering techniquesalso may be used to create a stream or cloud of metal molecules orparticles in a vacuum. The molecules or particles created by vapourcoating are adhered to the backside of the microspheres. In this form,the reflective metal layer consists essentially of pure metal. There isno need for a resin matrix to support the metal particles. It is to beunderstood that in the case of aluminum, some of the metal may be in theform of the metal oxide and/or hydroxide. Aluminum and silver metals arepreferred because they tend to provide the highest retroreflectivebrightness. The metal layer should be thick enough to reflect incominglight. Typically, the reflective metal layer is about 50 to 150nanometers thick. Although the reflective color of a silver coating canbe brighter than an aluminum coating, an aluminum layer normally is morepreferred because it can provide better laundering durability whenadhered to a glass optical element.

Alternatively, the reflective layer may comprise reflective pigmentssuch as, for example, mica powder, metal particles or flakes orpearlescent type pigments.

Additional Layers

The retroreflective sheet may comprise further layers. As mentionedabove, a so-called light-transmissible intermediate layer can bepresent. A light-transmissible layer is typically arranged between themicrospheres and the reflective layer, e.g., a reflective metal layer.The light-transmissible intermediate layer can be provided to protectthe reflective element from corrosion and deterioration in itsreflective characteristics during exposure to the natural elementsand/or laundering. The intermediate layer preferably comprises atransparent polymeric layer having optical characteristics such asrefractive index which are selected so as to provide a functionalretroreflective optical system.

The light-transmissible intermediate layer generally comprises apolymeric material that may be the same as or different from thepolymeric material of the binder layer. To provide good launderingdurability, the polymer preferably is a crosslinked polymer. Examples ofpolymers that may be suitable include those that contain units ofurethane, ester, ether, urea, epoxy, carbonate, (meth)acrylate, acrylic,olefin, vinyl chloride, amide, alkyd, or combinations thereof.

The polymer that is used in the light-transmissible intermediate layermay have functional groups that allow the polymer to be linked to thesilane coupling agent, or the reactants that form the polymer maypossess such functionality. For example, in producing polyurethanes, thestarting materials may possess hydrogen functionalities that are capableof reacting with an isocyanate-functional silane coupling agent; see forexample, U.S. Pat. No. 5,200,262 (Li). Preferred polymers arecrosslinked poly(urethane-ureas) and crosslinked poly(acrylates). Thesepolymers can maintain their properties under the rigors of theindustrial laundering process and when being worn as clothing.

Poly(urethane-ureas) may be formed by reacting a hydroxy-functionalpolyester resin with excess polyisocyanate. Alternatively, apolypropylene oxide diol may be reacted with a diisocyanate and thenwith a triamino-functionalized polypropylene oxide.

Crosslinked poly(acrylates) may be formed by exposing acrylate oligomersto electron beam radiation; see for example, U.S. Pat. No. 5,283,101(Li).

Examples of commercially available polymers that may be used in thelight-transmissible intermediate layer include: Vitel™ 3550 availablefrom Shell Oil Company, Akron, Ohio; Ebecryl™ 230 available from UBCRadcure, Smryna, Ga.; Jeffamine™ T-5000, available from HuntsmanCorporation, Houston, Tex.; and Arcol™R-1819, available from ArcoChemical Company, Newtown Square, Pa.

The thickness of the light-transmissible intermediate layer is generallyselected such that incident light can be focussed on the reflectivemetal layer by the microspheres. The light-transmissible intermediatelayer typically has an average thickness from about 5 nanometers to 1.5times the average diameter of the microspheres. Preferably, thelight-transmissible intermediate layer has an average thickness fromabout 100 nanometers to about the average diameter of the microspheres.More preferably, the light-transmissible intermediate layer's averagethickness is about one (1) micrometer to about 0.25 times the averagediameter of the microspheres. The light-transmissible intermediate layerthickness may be greater between the microspheres than on themicrospheres. The light-transmissible intermediate layer preferably iscontinuous, but there may be some very small regions—particularly at themost embedded portion of the microspheres—where the light-transmissibleintermediate layer is discontinuous, i.e., its thickness is zero orapproaches zero. Thus, the light-transmissible intermediate layer isconveniently continuous or substantially continuous.

Further additional layers can be present in the retroreflective sheet.These layers may for example serve to provide additional support andhandleability of the reflective sheet or may be present to provideadhesion characteristics to be used for attachment of the reflectivesheet to a substrate such as a safety garment or accessory. Examples ofadditional layers include a woven or non-woven web, a heat-activatedadhesive layer, a pressure-sensitive adhesive layer or combinations ofthese layers. Particularly preferred is the use of a woven web as anadditional layer so that a reflective fabric is generated.

A woven or non-woven web may be composed of any known fiber materialsincluding for example polyamide, polyester, polyacrylate,polyacylonitrile fibers as well as natural fibers such as cotton. Mixedfibers including mixed synthetic and natural fibers can be used as well.

Suitable adhesive layers for use with the reflective sheet include forexample, a heat-activated adhesive, comprising a polyester, polyurethaneor vinyl-based polymer, or a normally tacky pressure-sensitive adhesivecomprising an acrylic polymer, a rubber-resin based system or asilicone-based polymer.

Specific combinations of additional layers include 1) apressure-sensitive adhesive layer with a fabric and 2) apressure-sensitive adhesive layer in combination with a heat-activatedadhesive layer. In order to protect the adhesive layer, a protectiveliner, such as a siliconised paper liner, may be used. In the twocombinations just described, the pressure-sensitive adhesive is arrangedso that it is exposed in order to form a bond with the substrate orgarment.

Various constructions of the retroreflective sheet may be used. Forexample, in a first embodiment, the retroreflective sheet comprises alayer of microspheres partially exposed at the first major surface ofthe retroreflective sheet to air, a light-transmissible intermediatelayer, a metal layer as the reflective layer and a binder layer. In thisfirst embodiment of the retroreflective sheet, light falls upon thesurface of the microspheres, is focussed upon the reflective metal layerlocated at a specific distance behind the non-exposed part of themicrosphere through the selected thickness of the light-transmissibleintermediate layer and is then reflected back through the microsphere tothe observer. Accordingly, a highly retroreflective sheet is obtained.On the binder layer there may be provided additional layers such as forexample a woven or non-woven web.

In a second embodiment of the retroreflective sheet, the reflectivelayer comprises a reflective metal layer that is provided directly onthe microspheres and that thus generally follows the contours of thenon-exposed part of the microspheres. No light-transmissibleintermediate layer is present. The reflective layer in this embodimentcomprises a thin metal layer preferably applied directly to thenon-exposed part of the microspheres by vacuum-deposition techniques.Typically, a binder layer and additional layers are further provided onthe thin metal layer as in the first embodiment.

The manufacture of retroreflective sheets is well known in the art.Open-bead retroreflective sheets can be made according to the teachingsof EP 759 179 or EP 1 262 802.

The retroreflective sheets can be applied to a variety of substrates.Often the substrate is, or becomes, the outer surface of an article ofclothing, so that the retroreflective sheet is displayed when theclothing is worn in its normal orientation on a person. The substratemay be, for example, a woven or nonwoven fabric such as a cotton fabric;a polymeric layer including nylons, olefins, polyesters, cellulosics,urethanes, vinyls, acrylics, rubbers; leather; and the like. Onepreferred substrate for use in the invention is a polyester nylon tricotknitted fabric treated with a fire retardant material. The substratealso could be rigid, metal surface such as the body of a motor vehicle,the walls of a truck trailer, or the surface of a helmet.

Retroreflective sheets for use in the invention may be applied to asubstrate using a variety of methods. In one method, the binder layer ofthe retroreflective sheet is heat laminated directly to the underlyingsubstrate. Alternatively, the retroreflective sheet may be mechanicallysecured to the substrate by, for example, sewing. In some applications,however, it is desired to secure the sheet to the substrate by use of anadhesive layer disposed on the back or second surface of the binderlayer. The adhesive layer may be a pressure-sensitive adhesive, aheat-activated adhesive, or an ultraviolet-radiation-activated adhesive.A fire retardant material, such as a brominated biphenol (for example,decabromodiphenyl oxide, Saytex™ 102E, Ethyl Corporation, Baton Rouge,La.), can be placed in the adhesive.

Treatment Method

In the treatment method, the retroreflective sheet is contacted with thetreatment composition comprising fluorinated compound comprising silaneand one or more auxiliary compounds at the major surface having theexposed microspheres. The treatment composition is generally applied tothe surface of the reflective sheet in amounts sufficient to produce acoating that yields a desired water repellency and/or improvement of thereflective properties, especially after repeated launderings and underrainfall conditions. This coating can be extremely thin, e.g., 1 to 50molecular layers, though in practice a useful coating may be thicker.

In one embodiment, the treatment composition comprising fluorinatedsilane and the auxiliary compounds is prepared as a solution ordispersion in water. Therefor, a mixture of fluorinated silane and theauxiliary compounds is vigorously stirred in water at neutral pH,typically at a temperature between 20 and 70° C., preferably between 30and 65° C. and during a time sufficient to dissolve or disperse theproducts. Additional emulsifiers can be used to increase the dispersionstability. Conventional cationic, non-ionic, anionic and zwitterionicemulsifiers are suitable. The emulsifier can be used in an amounteffective to stabilize the dispersion and will preferably by used in anamount of about 0 to 25 parts by weight, preferably about 5 to about 10parts by weight, based on 100 parts by weight of the composition. Othercomponents, such as silica or TiO₂, can be present, as well as otheraqueous water extenders known to those skilled in the art. Examplesinclude melamines, urethanes and the like.

As an alternative, the treatment composition may be applied as adispersion or solution in solvent. The organic solvent may comprise asingle organic solvent or a mixture of two or more organic solvents. Thesolvent(s) used in the composition preferably include those that aresubstantially inert (i.e., substantially nonreactive with thefluorinated silane and non-destructive for the retroreflective sheet).Suitable organic solvents, or mixtures of solvents can be selected fromaliphatic alcohols, having 1 to 4 carbon atoms, such as methanol,ethanol, isopropylalcohol; ketones such as acetone or methyl ethylketone; esters, such as ethyl acetate; ethers, such as diethyl ether,diisopropylether and methyl t-butylether and halogenated solventsincluding fluorinated solvents. Examples of suitable fluorinatedsolvents include fluorinated hydrocarbons, such as perfluorooctane,partially fluorinated hydrocarbons, such as pentafluorobutane;hydrofluoroethers, such as methyl perfluorobutyl ether and ethylperfluorobutyl ether. Various blends of fluorinated organic solventswith non-fluorinated organic solvents or other halogenated solvents canbe used.

To achieve good durability, particularly with respect to mechanicalwashing or laundering, the solutions or dispersions in solventpreferably also include water. Typically, the amount of water will bebetween 0.1 and 20% by weight, preferably between 0.5% by weight and 15%by weight, more preferably between 1 and 10% by weight.

The compositions used in the treatment method of the present inventionmay also include an acid or base catalyst. The acid catalyst, ifpresent, comprises an organic or inorganic acid. Organic acids includeacetic acid, citric acid, formic acid and the like. Examples ofinorganic acids include sulphuric acid, hydrochloric acid and the like.The acid will generally be included in the composition in an amountbetween about 0.01 and 10%, more preferably between 0.05 and 5% byweight. The base catalyst, if present, comprises for example sodium orpotassium hydroxide.

The treatment composition is typically a relatively diluted solution ordispersion, containing between 0.05 and 30 percent by weight, preferablybetween 0.05 and 20 percent by weight, and more preferably between 0.1and 5 percent by weight of fluorinated compound and auxiliary compounds.

A wide variety of coating methods can be used to treat the surface of aretroreflective sheet. The methods include spraying, dipping, gravureprinting, screen printing, tampon printing, transfer coating, knifecoating, kiss coating and Foulard application techniques. Preferredmethods include Foulard application and spraying. A particular preferredmethod is kiss coating, as described in EP 1,262,802. The surface of theretroreflective sheet can further be treated and/or retreated during oneor more laundry cycles in a laundering machine. Therefore, the treatingcomposition, typically as an aqueous emulsion will be added during thelast rinsing of a laundering cycle.

A drying step is typically incorporated into the method to allow forremoval of the solvent and/or water to produce the finished coating offluorinated silane and auxiliary compounds on the surface of theretroreflective sheet. The drying steps may comprise one or more phaseseffecting evaporation of solvents and/or water under ambient conditionsand/or utilization of forced air ovens at elevated temperatures toaccelerate removal of solvents and/or water and/or accelerate thereaction of the fluorinated silane compound with the auxiliary compoundsand with the surface of the retroreflective sheet. Preferably, thetreated retroreflective sheet will be subjected to a temperature ofbetween 50° C. and 180° C. and for a time sufficient to dry and cure thetreated retroreflective sheet.

The following examples further illustrate the invention without theintention however to limit the invention thereto.

EXAMPLES

The following examples further illustrate the invention without theintention however to limit the invention thereto. All parts are byweight unless indicated otherwise.

Abbreviations

-   MeFBSEMA: N-methyl perfluorobutyl sulfonamido ethylmethacrylate-   MeFBSEA: N-methyl perfluorobutyl sulfonamido ethylacrylate-   A-160: HS(CH₂)₃Si(OCH₃)₃, available from Aldrich-   A-174: CH₂═C(CH₃)C(O)O(CH₂)₃ Si(OCH₃)₃, available from Aldrich-   L31: polymethylhydrosilane, available from GE Chem Specialties-   TEOS: tetraethoxysilane-   EHT: Tetra(2-ethylhexyl)ortho titanate-   ABIN: azo-bisisobutyronitrile-   MEK: methylethyl ketone-   Arquad 2HT/75: dicocodimethylammoniumchloride, available from Akzo-   PES/CO fabric: 65/35 polyester/cotton fabric, having a weight of 215    g/m², available from Lauffenmühle GmbH    Test Methods    Measurement of Retroreflectivity of Retroreflective Sheets, R′

Reflectivity of the retroreflective sheet was measured according to theInternational commission on Illumination or CIE (CommissionInternationale de l'éclairage) 54: 1982 Retroreflection: Definition andMeasurement. Samples were measured at an observation angle (α) of 0.2°and an entrance angle (β1) of 5°. Results were recorded in candela perlux per sq. meter (cd/lx/m²).

Measurement of Wet Retroreflectivity of Retroreflective Sheets, R′

In order to measure wet retroreflectivity, 10×10 cm² samples ofretroreflective sheets were sewn onto PES/CO fabric (65/35) beforetesting.

Measurement of the retroreflectivity of retroreflective sheets undersimulated rainfall conditions was performed in general according to theCIE method above but under conditions described specifically in EN 471ANNEX A—Method of Measuring Wet Retroreflective Performance. Themeasurement was made after 5 minutes continuing simulated rainfall.

Samples were measured at an observation angle (α) of 0.2° and anentrance angle (β1) of 5°. Results were recorded in cd/lx/m².

Spray Rating (SR) and ΔWeight (g)

The spray rating of a treated substrate is a value indicative of thedynamic repellency of the treated substrate to water that impinges onthe treated substrate. The repellency of 18×15 cm² weighed samples wasmeasured by Standard Test Number 22, published in the 1985 TechnicalManual and Yearbook of the American Association of Textile Chemists andColorists (AATCC), but using a slightly different ‘spray rating’ for thetested substrate. The spray rating was obtained by spraying 250 ml wateron the substrate from a height of 15 cm. The wetting pattern wasvisually rated using a 0 to 100 scale, where 0 meant complete wettingand 100 meant no wetting at all. A value of 80 meant that duringspraying, some incontinuous rays and some drops of water were noticed onthe panel. The panel were weighed before and after the test (afterremoval of not adhered water). The weight increase was reported asΔweight (g). The samples were prepared in triplicate and the valuesreported are the average of the three measurements.

Contact Angles (°)

The treated retroreflective sheets were tested for their contact anglesversus water (W) and n-hexadecane (O) using an Olympus TGHM goniometer.The contact angle with water reflects the water repellency of thecoating; the contact angle with hexadecane is indicative of anti-soilingand anti-staining properties. The contact angles were measured before(initial) and directly after abrasion (abrasion). The values are themean values of 4 measurements and are reported in degrees. The minimummeasurable value for a contact angle was 20. A value <20 meant that theliquid spread on the surface.

Washing Procedure for Retroreflective Sheets

Home Laundering:

Samples of treated and untreated retroreflective sheets (100 cm²) weresewn to 65/35 PES/CO fabric. The fabrics were laundered according to ISO26330 Textiles—Domestic Washing and Drying Procedures for TextileTesting. Washing was performed in domestic washing machines at 60° C.and the number of cycles is given in the data tables below.

Industrial Laundering:

Both treated and untreated samples of retroreflective sheets werelaundered according to ISO 15797 (8) and tunnel finishing, for 30cycles.

Materials Employed in the Examples

Fluorinated Compounds Having One or More Silyl Groups (FC):

(A) Fluorinated Pligomer Silane MeFBSEMA/A-160 8/1:

In a three-necked flask of 1000 ml, fitted with a condenser, stirrer,thermometer, heating mantle and heating control were placed 425 g (1mole) MeFBSEMA and 24.54 g (0.125 moles) A-160, 300 g ethylacetate and0.9 g ABIN.

The mixture was degassed three times using aspirator vacuum and nitrogenpressure. The mixture was reacted under nitrogen at 80° C. during 8hours. A clear solution of the oligomeric fluorochemical silaneMeFBSEMA/A-160 in a molar ratio of about 8/1 was obtained. Unlessotherwise indicated, the solvent was not evaporated before use in thetreatment composition.

(B) Fluorinated Oligomer Silane MeFBSEA/A-174/A-160 4/1/1:

In a three-necked flask of 500 ml, fitted with a condenser, stirrer andthermometer, were placed 41.1 g (0.1 moles) MeFBSEA, 6.2 g (0.025 moles)A-174, 4.9 g (0.025 moles) A-1 60, 35 g ethylacetate and 0.1 g ABIN. Themixture was degassed three times using aspirator vacuum and nitrogenpressure. The mixture was reacted under nitrogen at 75° C. during 8hours. An additional 0.05 g ABIN was added and the reaction wascontinued for another 3 hrs at 75° C.; another 0.05 g ABIN was added andthe reaction continued at 82° C. for 2 hrs. A clear solution of theoligomeric fluorochemical silane MeFBSEA/A-174/A-160 in a molar ratio4/1/1 was obtained. Unless otherwise indicated, the solvent was notevaporated before use in the treatment composition.

(C) Fluorinated Polyether Disilane

Fluorinated polyether disilane (C) was prepared by reactingperfluoropolyetherdiester CH₃OC(O)CF₂(CF₂O)₉₋₁₁ (CF₂CF₂O)₉₋₁₁CF₂C(O)OCH₃ (with an average molecular weight of about 2000),commercially available from Ausimont, Italy, under the trade designationZ-DEAL, with 3-aminopropyltriethoxysilane, available from AldrichCompany Co., as taught in U.S. Pat. No. 3,810,874 (Mitsch et al.), Table1, line 6. The exothermic reaction proceeded readily at roomtemperature, simply by mixing the starting materials. The progress ofthe reaction was monitored by infrared analysis. Unless otherwiseindicated, after reaction, 10 parts of fluorinated polyether disilanewere mixed with 60 parts TEOS and 30 parts ethanol. This mixture,indicated as FC(C) was used in the examples.

Examples 1 to 4 and Comparative Examples C-1 and C-2

In Examples 1 and 3, retroreflective fabric web described above in thesection on the retroreflective sheet as the first (1) and second (2)embodiment of the retroreflective sheet were treated with a mixture of0.1 g fluorinated compound (B), 0.6 g TEOS, 3 g acetic acid, 1.5 g waterand 100 g ethanol by spray application at about 20 ml./min. In Examples2 and 4, retroreflective fabric web of the first (1) and second (2)embodiment were treated with a mixture of 1 g FC (C) (containing 0.1 gfluorinated polyether disilane (C), 0.6 g TEOS and 0.3 g ethanol), 3 gacetic acid, 1.5 g water and 100 g ethanol. After spraying, thesubstrates were dried and cured at 120° C. for 5 min. For ComparativeExamples C-1 and C-2, untreated retroreflective sheets of the first (1)and second (2) embodiment respectively, were used. In ComparativeExample C-3, retroreflective fabric wet of the first embodiment wastreated by spray application, with a mixture of 0.1 g fluorochemicaldisilane (C), 0.3 g acetic acid,1.5 g water and 100 g ethanol. Thecontact angles were measured initially and after abrasion, using anErichsen cleaning machine, 3M High Performance wipe available from 3MCompany) and Mister Propre cleaner (available from Henkel), using 5000cycles. The results are given in Table 1. TABLE 1 Contact angles ofretroreflective sheet Retro- reflective Contact angles (°) Ex.Fluorinated fabric of DI-water n-hexadecane No. compound embodimentInitial Abraded Initial Abraded 1 B 1 108 80 67 50 2 FC (C) 1 102 90 6355 3 B 2 100 82 62 50 4 FC (C) 2 106 92 65 55 C-1 / 1 75 53 <20 <20 C-2/ 2 85 55 <20 <20 C-3 C 1 92 70 65 45

The results indicated that retroreflective sheets having high waterrepellency were obtained, both initial and after extended abrasion. Theaddition of a non-fluorinated auxiliary compound clearly improves thewater repellency. The treated retroreflective sheets further showed highanti-soiling properties as was reflected by the contact angles towardscyclohexane.

Examples 5 and 6 and Comparative Example C-4

In Examples 5 and 6, 18×15 cm² panels of retroreflective fabricaccording to the second embodiment and sewn onto PES/CO fabric, weretreated with a solution of 0.02 g L31, 0.05 g fluorinated oligomersilane (A), 10 g MEK and 0.02 g TEOS (ex 5) or 0.02 g EHT (ex 6), usinga K1 coating bar (available from RK Print-Coat Instruments, Ltd.SouthView Laboratories, Litlington, Royston, Herts SG8 0QZ UK) providing 6g/m². The samples were allowed to dry at room temperature for 3 min andwere cured at 100° C. for 10 min. Comparative Example C-4 was made withuntreated retroreflective sheet of the second embodiment. Initial waterrepellency was measured; the mean values of 3 measurements are recordedin Table 2. The durability of the wet reflectance after repeated homelaunderings was measured according to EN 471, Annex A. The results arerecorded in Table 3 (mean values of the results of duplicated panels).TABLE 2 Initial water repellency Example SR Δ weight (g) 5 80 0.07 6 800.04 C-4 70 0.15

TABLE 3 Durability of retroreflectance (EN 471, Annex A)Retroreflectance R′ (cd/lx/m²) Example Dry 2 min wet 5 min wet No homelaundering 5 697 548 531 6 649 525 504 C-4 626 443 423 20 homelaunderings (60° C.) 5 495 308 283 6 515 329 302 C-4 520 318 269 25 homelaunderings (60° C.) 5 540 347 324 6 482 267 246 C-4 511 251 153 30 homelaunderings (60° C.) 5 500 297 247 6 484 233 146 C-4 493 246 113 35 homelaunderings (60° C.) 5 523 280 190 6 481 227 141 C-4 479 139 94

The results indicated that the retroreflective sheets, treated with acomposition comprising a fluorinated compound and auxiliary compoundshad highly durable retroreflective properties. The retroreflectanceremained high, even after repeated home launderings. Also high wetretroreflectance was noticed.

Examples 7 and 8 and Comparative Examples C-5 and C-6

In Examples 7 and 8, retroreflective fabric webs according to the first(1) and second (2) embodiment were coated with a solution of 0.2 g L31,0.88 g of a 56.9% fluorinated oligomer solution (A) as prepared aboveand 0.2 g TEOS, dissolved in 100 g MEK, using a K1 coating bar (6 g/m²).The samples were allowed to dry for 10 min and were cured at 100° C.during 10 min in a Heraeus drying oven, model 2721. Comparative ExamplesC-5 and C-6 were made with untreated retroreflective sheets of the firstand second embodiment. The reflective properties of the treatedretroreflective fabric were evaluated after 45 home launderings. Theresults are given in Table 4. TABLE 4 Durability of retroreflectanceafter 45 home launderings (EN 471, Annex A) Retroreflective web ofRetroreflectance R′ (cd/lx/m²) Ex. No. embodiment Dry 2 min wet 7 2 518108 8 1 432 224 C-5 2 508 38 C-6 1 545 45

The results in the table indicate that the treated retroreflectivesheets showed a considerable improvement in wet reflectance, compared tountreated retroreflective sheets after 45 home launderings.

Examples 9 and 10

In Examples 9 and 10, retroreflective fabrics of the first and secondembodiment, sewn against PES/CO fabric were treated with a mixture ofprecondensed TEOS, fluorinated oligomer solution (A) and compound havingSi—H group. In a first step, the precondensation of TEOS was done bymixing and stirring 50 g TEOS, 44 g ethanol, 2.17 g DIWater and 0.27 gHCl (37%) for 48 hours in a 125 ml reaction flask. The solvent wasstripped off at 1 mm Hg pressure during 1 hour at 53° C. In a secondstep, the treatment composition was prepared. Therefore, 0.2 g of thereaction product, prepared in the first step, was dissolved in 100 gMEK, together with 0.2 g L31 and 0.88 g of a 56.9% fluorinated oligomersilane solution (A). This mixture was coated onto retroreflectivefabrics using a K1 coating bar (6 g/m²). The samples were allowed to dryfor 10 min and were cured at 100° C. during 10 min in a Heraeus dryingoven, model 2721. The reflective properties of the treatedretroreflective fabric were evaluated after 45 home launderings. Theresults are given in Table 5. TABLE 5 Retroreflectance after 45 homelaunderings (acc. to EN 471, Annex A) Retroreflective web ofRetroreflectance R′ (cd/lx/m²) Ex. No. embodiment Dry 2 min wet 9 2 52583 10 1 437 205 C-5 2 508 38 C-6 1 545 45

The results indicated that highly durable retroreflectance could beobtained with a treatment composition comprising fluorinated compound,precondensed TEOS and SiH group containing compound.

Examples 11 to 14

The treated retroreflective sheets as prepared in Examples 7-10 weretested for their resistance to industrial laundering cycles (30 cycles).The durability was tested with and without re-treatment after 20 cycles.For the re-treatment after 20 cycles, for Examples 11 and 13, emulsionswere prepared comprising fluorinated oligomer silane (A), TEOS and L31.In a first step, 30 g Arquad 2HT/75 and 300 g ethylacetate were stirredand heated until a clear emulsion was formed (55° C.). 100 g TEOS wereadded as well as 400 g of a 60% fluorinated oligomer silane solution(A). After stirring, the mixtures turned homogeneous. 100 g L31 wereadded and the mixtures were heated to 60° C. In a separate flask, 10 gof a 5 g/l aqueous solution of detergent for industrial laundering (asdescribed in ISO 15797, annex A1) was added to 880 g DI water. Themixture was stirred and heated to 47° C. The fluorochemical mixtureprepared above was slowly added to the detergent mixture under vigorousstirring. The stable pre-emulsion was poured into a MG-emulsifier (typeLAB60-10TBS), set at 55° C. and a pressure of 260/20 bar. After theemulsion passed a first time, it was poured again in the MG for a secondpass. The emulsion became viscous. DIWater was added to obtain 1920 gtotal. The emulsion was stripped at 46° C. using a rotavapor to obtain a28% solids emulsion. The treatment emulsions for Examples 12 and 14 weremade according to the same method, but using precondensed TEOS (asprepared in Examples 9 and 10). For all Examples, 10 ml/l water of theemulsions was added to the container of an industrial launderingmachine, assigned for the addition of softener, during the last rinsingof the 20^(th) industrial laundering cycle. The samples were dried in abatch drier. The performance was tested after 10 additional industrialwashings. The reflectance was measured and compared to the same samplesthat were subjected to 30 laundry cycles without re-treatment after 20cycles. The results are given in Table 6. TABLE 6 Retroreflectance after30 cycles industrial laundering (acc. to EN 471, Annex A)Retroreflectance (R′) (cd/lx/m²) No Re-treatment re-treatment after 20cycles Treatment After After Ex. No. of ex Dry 2 min (wet) Dry 2 min(wet) Retroreflective fabric of 2^(nd) embodiment 11 7 207 102 224 13012 9 165 72 233 134 Retroreflective fabric of 1^(st) embodiment 13 8 10970 138 92 14 10 139 94 154 107

Retroreflective fabric sheets with high retroreflectance were obtained,even after 30 industrial launderings. Depending on the retroreflectivefabric, further improvement can be obtained by re-treating the treatedsubstrates with an additional amount of fluorochemical composition.

1. Composition comprising: (i) a fluorinated compound having one or morefluorinated groups and one or more silyl groups that have one or morehydrolysable groups; and (ii) an auxiliary compound selected from thegroup consisting of organic compounds having a Si—H group. 2.Composition according to claim 1 further comprising one or morenon-fluorinated compounds of an element M selected from the groupconsisting of Si, Ti, Zr, B, Al, Ge, V, Pb and Sn having at least onehydrolysable group per molecule.
 3. Composition according to claim 2said non-fluorinated compound corresponds to the formula:(R)_(i)M(Y)_(j-i) wherein R represents a non-hydrolysable group, Mrepresents an element selected from the group consisting of Si, Ti, Zr,B, Al, Ge, V, Pb and Sn, j is 3 or 4 depending on the valence of M, i is0, 1 or 2, and Y represents a hydrolysable group.
 4. Compositionaccording to claim 1 wherein said compound comprising a —SiH group is apolysiloxane.
 5. Composition according to claim 4 wherein saidpolysiloxane corresponds to the formula:

wherein R¹, R², R³, R⁶, R⁷, R⁸ and R⁹ each independently representshydrogen, an alkyl or an aryl group, R⁴ and R⁵ each independentlyrepresents an alkyl or aryl group, x represents a value of 0 to 150, yrepresents a value of 0 to 150 and with the proviso that when x=0, atleast one of R¹, R², R⁶, R⁷, R⁸ and R⁹ represents a hydrogen atom. 6.Composition according to claim 1 wherein said composition comprises anaqueous dispersion of said fluorinated compound and said auxiliarycompound.
 7. Composition according to claim 1 wherein said compositioncomprises a dispersion or solution of said fluorinated compound and saidauxiliary compound in an organic solvent.
 8. Composition according toclaim 1 wherein said fluorinated compound comprises one or morefluorinated polyether groups.
 9. Composition according to claim 1wherein said fluorinated compound comprises an oligomer derived from apolymerization of at least one fluorinated monomer in the presence of achain transfer agent and optionally one or more non-fluorinated monomersand wherein said oligomer comprises at least one silyl group that hasone or more hydrolysable groups.
 10. Composition according to claim 9wherein said oligomer is derived from a polymerization of at least onefluorinated monomer and one or more non-fluorinated monomers in thepresence of a chain transfer agent and wherein at least one of saidnon-fluorinated monomers and/or said chain transfer agent comprises asilyl group that has one or more hydrolysable groups.
 11. Compositionaccording to claim 10 wherein said hydrolysable groups are independentlyselected from the group consisting of halogens, alkoxy groups, aryloxygroups and acyloxy groups.